1. Field of the Invention
The present invention relates to a tire curing forming mold in which an annular mold portion brought into contact with a tread portion of a tire is structured by sectors which are divided in a tire circumferential direction.
2. Description of the Related Art
A tire curing forming mold (hereinafter, there is a case of being simply referred to as a forming mold) is structured by combining a plurality of mold portions, and is broadly classified into a two-piece type and a segmented type on the basis of a divided aspect. A portion brought into contact with a tread portion of a tire in the forming mold is divided in a tire width direction in the two-piece type, however, is divided in a tire circumferential direction in the segmented type. Due to a difference of the structure, the segmented type is more excellent in a mold releasing characteristic of the tire.
FIG. 10 is a vertical cross sectional view schematically showing one example of the segmented type forming mold. This forming mold is provided with a lower mold portion 41 and an upper mold portion 42 which are brought into contact with a side wall portion SW of a tire T2, and an annular mold portion 44 which is brought into contact with a tread portion Tr2. The annular mold portion 44 is constituted by a combination of a plurality of sectors 43 which are divided in a tire circumferential direction, and a concavo-convex shape corresponding to a tread pattern is provided in a tread forming surface provided on an inner peripheral side thereof. Each of the sectors 43 is structured to be displaceable in a tire diametrical direction, and each of the sectors 43 displaces to an inner side in the tire diametrical direction at a time of giving way to a mold clamped state from a mold released state, thereby bringing end surfaces into pressure contact with each other so as to be connected annularly.
In this case, in the segmented type forming mold, since each of the sectors brings the end surface into pressure contact with each other each time of the transition motion to the mold clamped state, the end surface of the sector tends to be worn out early by repeating an opening and closing motion. This tendency is significant particularly in a case where the sectors are made of a comparatively soft material such as an aluminum material or the like. Further, if the attrition of the end surface of the sector makes progress, a contact characteristic between the sectors is lowered, and a gap is provided in the divided surfaces. Accordingly, there is a case that a rubber burr called as a flash is generated in the tread surface of the tire.
Since this flash not only deteriorates an outer appearance of the tire, but also deteriorates uniformity and lowers drainage property in a groove portion, it is necessary to remove the flash, however, the removing work is very complicated because of a manual work. Further, at a time of repairing the end surface of the attrited sector, it is necessary to carry out a weld overlay to the attrited portion, so that there is generated a problem that a man hour and a cost are increased. Further, since the tire can not be cured during the repairing period, it is actually hard to immediately repair the sector even if the flash generation is confirmed. Particularly, in a case of making an expert maker a request of repairing the end surface of the sector, there is a case that an awaiting repair status is generated by a free condition of the maker, a capacity and the like, and there is a case that the complicated work is forced for a long period.
Japanese Unexamined Patent Publication No. 1-29686, Japanese Unexamined Patent Publication No. 4-341806, and Japanese Unexamined Patent Publication No. 2005-178121 describe a tire curing forming mold in which an annular mold portion is constituted by sectors which are divided in a tire circumferential direction, however, none of them discloses a countermeasure technique of the attrition on the end surface of the sector as mentioned above.